1. Field of the Invention
The present invention relates to fuel cell power systems and more particularly to MEMS (microelectronic mechanical systems) based fuel cell structures on the chip with integrated functional power conditioning circuitry for converting, conditioning and regulating the output power.
2. Background Information
As personal portable computer electronics become smaller and smaller, there is a need to power the electronics with batteries or battery equivalents (i.e. fuel cells) which provide higher power densities.
Fuel cells and their control have been developed for many years. One such example is found in U.S. Pat. No. 6,387,556 that describes a fuel cell power system including a controller that monitors and controls the fuel cell operation. This patent is incorporated herein by reference.
Microelectronic mechanical systems (MEMS) have progressed to forming chanels and membranes for implementing fuel cells at the chip level. An example is found in U.S. Pat. No. 6,312,846, by Marsh. This patent discloses fuel cell structures formed on the same wafer (the large substrate upon which many individual integrated circuit chips are formed). Typically the individual chips are cut out from to wafer and packaged individually. However, Marsh shows different functional circuits formed on different chips where the different chips remain on the same wafer. Interconnections then may be made by discrete wiring or deposition between the chips. These chips provide functions that include power conversion, conditioning and regulation. Power conversion, conditioning and regulation are used redundantly herein and in the art where the terms “conditioning,” “conversion,” and “regulation” may each include or exclude the other two depending on context.
One limitation of the Marsh technology is that practical implementations will be large since large sections of the wafer must be used, and wafers may be four, eight, or more inches in diameter. These large sections include spacing between the different chips where interconnections must run to make electrical connections. These interconnections require additional steps and associated costs.
The prior art as evidenced by the above referenced U.S. patents describe how to fabricate fuel cell structures as described at the chip level. It is well known to use separate electronics packages to provide the conversion, regulating and conditioning functions, where the separate packages are electrically interconnected using cables or soldered wires.
However, there is a continuing need to reduce the size, while providing higher power densities, of power systems for use in portable and the ever smaller computers and recreational and business electronics. Consistent with these needs, an objective of the present invention is to utilize a variety of electronic devices including switched mode or linear power supply circuitry for providing practical fuel cell power supplies in small packages with high power capabilities.